The driver installed on Windows 7 without an SD card in. Once I installed it, I then put the card back in the reader.

To install the firmware, the Sony updater failed so I had to manually unzip and copy the package to the reader root before rebooting the device into recovery which then successfully installed the firmware.

All working great, thanks.

Update: Decided to unroot after all this as the Kindle app is pretty slow compared to my old kindle keyboard that I will continue to use.

Only for clarify and future references, you can repartitioning your device with version 1.0.07, since the first entrance of this topic talks about downgrade device in order to use for partitioning, this is not necesary, you can do it from 1.0.07 version, I recommend repartitioning using Linux Distro and only modify Partitions 3, 4 and 9.
Regards.